A case-control study of the joint effect of reproductive factors and radiation treatment for first breast cancer and risk of contralateral breast cancer in the WECARE study Journal Article
| Authors: | Brooks, J. D.; Boice, J. D. Jr; Shore, R. E.; Reiner, A. S.; Smith, S. A.; Bernstein, L.; Knight, J. A.; Lynch, C. F.; John, E. M.; Malone, K. E.; Mellemkjær, L.; Langballe, R.; Liang, X.; Woods, M.; Tischkowitz, M.; Concannon, P.; Stram, D. O.; on behalf of the WECARE Study Collaborative Group |
| Contributors: | Bernstein, J. L.; Capanu, M.; Orlow, I.; Robson, M. |
| Article Title: | A case-control study of the joint effect of reproductive factors and radiation treatment for first breast cancer and risk of contralateral breast cancer in the WECARE study |
| Abstract: | Objective: To examined the impact of reproductive factors on the relationship between radiation treatment (RT) for a first breast cancer and risk of contralateral breast cancer (CBC). Methods: The Women's Environmental Cancer and Radiation Epidemiology (WECARE) Study is a multi-center, population-based case-control study where cases are women with asynchronous CBC (N = 1521) and controls are women with unilateral breast cancer (N = 2211). Rate ratios (RR) and 95% confidence intervals (CI) were estimated using conditional logistic regression to assess the independent and joint effects of RT (ever/never and location-specific stray radiation dose to the contralateral breast [0, >0-<1Gy, ≥1Gy]) and reproductive factors (e.g., parity). Results: Nulliparous women treated with RT (≥1Gy dose) were at increased risk of CBC compared with nulliparous women not treated with RT, although this relationship did not reach statistical significance (RR = 1.34, 95% CI 0.87, 2.07). Women treated with RT who had an interval pregnancy (i.e., pregnancy after first diagnosis and before second diagnosis [in cases]/reference date [in controls]) had an increased risk of CBC compared with those who had an interval pregnancy with no RT (RR = 4.60, 95% CI 1.16, 18.28). This was most apparent for women with higher radiation doses to the contralateral breast. Conclusion: Among young female survivors of breast cancer, we found some evidence suggesting that having an interval pregnancy could increase a woman's risk of CBC following RT for a first breast cancer. While sampling variability precludes strong interpretations, these findings suggest a role for pregnancy and hormonal factors in radiation-associated CBC. © 2020 The Author(s) |
| Keywords: | contralateral breast cancer; reproductive factors; radiation treatment; wecare study |
| Journal Title: | Breast |
| Volume: | 54 |
| ISSN: | 0960-9776 |
| Publisher: | Elsevier Inc. |
| Date Published: | 2020-12-01 |
| Start Page: | 62 |
| End Page: | 69 |
| Language: | English |
| DOI: | 10.1016/j.breast.2020.07.007 |
| PROVIDER: | scopus |
| PMCID: | PMC7494790 |
| PUBMED: | 32927238 |
| DOI/URL: | |
| Notes: | Article -- Export Date: 1 October 2020 -- Source: Scopus |
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